In recent years, some mobile devices incorporate a function referred to as “security lock function”. The “security lock function” is a function to automatically set a mobile device to a mode for rejecting inputting operations from button keys and a touch panel on the mobile device, i.e., a mode for invalidating inputting operations (keeping the mobile device locked), if the mobile device has not been operated for a given period of time. The security lock function has been developed for protecting many items of private information stored in recent mobile devices from third parties.
A mobile device with the security lock function is set to a locked state if it has not been operated for a certain period of time even when the user (other than the third parties) is using the mobile device.
For example, while the user is listening to music on the mobile device, the mobile device is set to a locked state when a certain period of time elapses. In order for the user to validate an inputting operation to fast-forward the content or change the sound volume subsequently, the user needs to make an operation to unlock the mobile device, which is a rather troublesome task.
There has been developed a technology for solving the above problem (see Patent Literature 1, for example). According to the technology, if the user wants to listen to music using a terminal device and a unit device (e.g., a headset with a near-range wireless communication capability), then while music data are being sent from the terminal device to the unit device, the terminal device is set to an unlocked state. When the terminal device and the unit device have not been connected continuously for a certain period of time, or when music data have not been sent from the terminal device to the unit device for a certain period of time, the terminal device is set to a locked state.